Hard
Rock

Millions of years of
evolution by natural selection has endowed the brain with a cruel web of negative-feedback
mechanisms to regulate our moods, emotions and degree of well-being. Taking refined
'recreational' euphoriants, notably cocaine or the amphetamines,
sends a signal to the brain that indicates, falsely, the impending arrival of
an immense evolutionary benefit.

After
the drug-fuelled high comes the crash. Genetically-driven feedback-inhibition
kicks in. Cocaine-withdrawal causes a protracted biochemical abstinence-syndrome
marked by craving, melancholy and anhedonia. Neuronal release of dopamine declines.
So does the number of mesolimbic dopamine transporters. The spontaneous firing
of dopamine cells decreases. Chronic cocaine dependence may cause long-lasting
functional deficits in the frontal cortex as well.